import java.util.Stack;
//括号匹配
public class Solution1 {
    public boolean isValid(String s) {
        Stack<Character> stack = new Stack<>();
        for(int i=0;i<s.length();i++){
            char ch = s.charAt(i);
            if(ch=='{'||ch=='['||ch=='('){
                stack.push(ch);
            }else{
                if(stack.empty()){
                    return false;
                }else{
                    char tmp = stack.peek();
                    if((ch==')'&&tmp=='(')||(ch==']'&&tmp=='[')||(ch=='}'&&tmp=='{')){
                        stack.pop();
                    }else{
                        return false;
                    }
                }

            }
        }
        if(!stack.empty()){
            return false;
        }
        return true;

    }
}